The present invention relates to a work vehicle and a control method of a work vehicle.
A work vehicle is provided with a hydraulic actuator and an operation member for operating the hydraulic actuator. An operator operates the hydraulic actuator using the operation member. In addition, a lock member for locking the operation of the hydraulic actuator by the operation member is provided in the work vehicle. For example, a lock lever is provided which is able to switch between a locked position and a release position in the work vehicle which is disclosed in Japanese Unexamined Patent Application Publication No. H11-21079. The operation of the hydraulic actuator is locked when the lock lever is operated to be in the locked position. Due to this, the hydraulic actuator is not activated even when the operator operates the operation lever. The lock of the hydraulic actuator is released when the lock lever is operated to be in the release position.
There is a possibility that the hydraulic actuator may carry out an unexpected action when the lock member is switched to the release position in a state where the operation member is operated in a position for carrying out activating of the hydraulic actuator (hereafter, referred to as an “activation position”) in the work vehicle provided with a lock member as described above. In order to prevent such activating of the hydraulic actuator, it is effective if the operation member detects positioning at the activation position when the lock member is switched to the release position.
In Japanese Unexamined Patent Application Publication No. H11-21079, the setting pressure of a primary side pressure switch of the operation lever is set to a pressure which is lower than the setting pressure of a secondary side pressure switch. Accordingly, the primary side pressure switch is turned on before the secondary side pressure switch when the lock lever is switched to the release position in a state where the operation lever is set in the activation position. That is, the operation member is determined to be positioned in the the lock lever is switched to the release position in a state where the operation lever is set in the activation position. That is, the operation member is determined to be positioned in the activation position due to the primary side pressure switch being turned on before the secondary side pressure switch.
However, it is not easy to obtain sufficient determination accuracy in the determination using pressure switches such as described above. The object of the present invention is to provide a work vehicle and control method of a work vehicle where it is possible to accurately determine whether or not an operation member is operated to be in an activation position when a lock member has been switched to a release position.
A work vehicle according to a first aspect of the present invention is provided with a hydraulic actuator, an operation member, a pilot valve, an actuator control valve, a lock member, a lock valve, a lock valve switching section, an elapsed time detection section, an elapsed time determination section, a pilot pressure determination section, and an erroneous operation monitoring section. The operation member is a member for operating the hydraulic actuator. The pilot valve outputs pilot pressure according to operation of the operation member. The actuator control valve controls the hydraulic actuator according to a pilot pressure which is input. The lock member is able to be switched a locked position and a release position. The lock valve is switched a released state and a locked state. The lock valve permits the supply of pilot pressure to the actuator control valve in the released state. The lock valve blocks the supply of pilot pressure to the actuator control valve in the locked state. The lock valve switching section switches the lock valve from the locked state to the released state when the lock member is switched from the locked position to the release position. The elapsed time detection section detects elapsed time from a point in time where the lock member is switched from the locked position to the release position. The elapsed time determination section determines whether or not the elapsed time is equal to or more than a predetermined time. The pilot pressure determination section determines whether or not the pilot pressure is equal to or more than a predetermined pressure. The erroneous operation monitoring section maintains the lock valve in the released state in a case where the pilot pressure is equal to or more than the predetermined pressure when the elapsed time is equal to or more than the predetermined time. The erroneous operation monitoring section switches the lock valve to the locked state in a case where the pilot pressure is equal to or more than the predetermined pressure when the elapsed time is less than the predetermined time.
A work vehicle according to a second aspect of the present invention is the work vehicle according to the first aspect where the predetermined time is a time until the pilot pressure rises to the predetermined pressure when the lock member is switched from the locked position to the release position in a state where the operation member is set in a position for activating the hydraulic actuator.
A work vehicle according to a third aspect of the present invention is the work vehicle according to the first aspect where the predetermined time is equal to or more than 0.2 seconds and equal to or less than 2 seconds.
A work vehicle according to a fourth aspect of the present invention is the work vehicle according to the first aspect where a hydraulic pump which supplies hydraulic fluid to the pilot valve is further provided. The lock valve is disposed in a fluid passage which connects the hydraulic pump and the pilot valve.
A work vehicle according to a fifth aspect of the present invention is the work vehicle according to the first aspect which is further provided with a controller, a pilot pressure detection section, the lock valve switching section, a first signal line, a second signal line, a third signal line, a relay, and a fourth signal line. The controller includes the elapsed time detection section, the elapsed time determination section, and the erroneous operation monitoring section. The pilot pressure detection section detects the pilot pressure. The lock valve switching section is linked to the activating of the lock member. The first signal line transmits a signal from the lock valve switching section to the lock valve. The second signal line transmits a signal from the lock valve switching section to the controller. The third signal line transmits a signal from the pilot pressure detection section to the controller. The relay is disposed in the first signal line. The fourth signal line transmits a signal from the controller to the relay.
A work vehicle according to a sixth aspect of the present invention is the work vehicle according to the first aspect where the pilot pressure is a first pilot pressure and the pilot valve outputs a plurality of pilot pressures which includes the first pilot pressure and a second pilot pressure which is output from a fluid passage which is different to the first pilot pressure. The erroneous operation monitoring section switches the lock valve to the locked state in a case where at least one of the pilot pressures from among the plurality of pilot pressures is equal to or more than the predetermined pressure when the elapsed time is less than the predetermined time.
A work vehicle according to a seventh aspect of the present invention is the work vehicle according to the first aspect where the erroneous operation monitoring section prohibits switching of the lock valve by the lock valve switching section as long as the lock member is not returned from the release position to the locked position when the elapsed time determination section determines that the elapsed time is less than the predetermined time.
A work vehicle according to an eighth aspect of the present invention is the work vehicle according to the first aspect which is further provided with a notification section. The notification section outputs notification with regard to the operator when the erroneous operation monitoring section switches the lock valve in the locked state.
A work vehicle according to a ninth aspect of the present invention is the work vehicle according to the first aspect which is further provided with a temperature detection section which detects a temperature of the hydraulic fluid. The elapsed time determination section increases the predetermined time as the temperature of the hydraulic fluid falls.
A work vehicle according to a tenth aspect of the present invention is the work vehicle according to any one of the first to the ninth aspects where the work vehicle is a hydraulic shovel which has a revolving body. The hydraulic actuator may be any one of a revolving motor which carries out revolution of the revolving body, a hydraulic motor for movement, a boom cylinder, an arm cylinder, or a bucket cylinder.
A control method according to an eleventh aspect of the present invention is a control method of a work vehicle. The work vehicle is provided with a hydraulic actuator, an operation member, a pilot valve, an actuator control valve, a lock member, and a lock valve. The operation member is a member for operating the hydraulic actuator. The pilot valve outputs pilot pressure according to operation of the operation member. The actuator control valve controls the hydraulic actuator according to a pilot pressure which is input. The lock member is able to be switched a locked position and a release position. The lock valve is switched a released state and a locked state. The lock valve permits the supply of pilot pressure to the actuator control valve in the released state. The lock valve blocks the supply of pilot pressure to the actuator control valve in the locked state. The control method is provided with the steps described below. The first step is switching the lock valve from the locked state to the released state when the lock member is switched from the locked position to the release position. The second step is detecting the elapsed time from a point in time when the lock member is switched from the locked position to the release position until the pilot pressure rises to the predetermined pressure. The third step is determining whether or not the elapsed time is equal to or more than a predetermined time. The fourth step is maintaining the lock valve in the released state when the elapsed time is equal to or more than the predetermined time. The fifth step is switching the lock valve to the locked state when the elapsed time is less than the predetermined time.
In a control method according to a twelfth aspect of the present invention, the lock valve is switched from the locked state, which prohibits activating of the hydraulic actuator, to the released state, which permits activating of the hydraulic actuator, when the lock member is switched from the locked position to the release position. Then, the lock valve is switched to the locked state in a case where the pilot pressure according to an operation of the operation member for operating the hydraulic actuator rises to a predetermined pressure within a predetermined time from a point in time when the lock member is switched from the locked position to the release position.
In the work vehicle according to the first aspect of the present invention, the erroneous operation monitoring section switches the lock valve from the locked state to the released state when the lock member is switched from the locked position to the release position. However, the erroneous operation monitoring section switches the lock valve to the locked state in a case where the pilot pressure is equal to or more than the predetermined pressure when the elapsed time is less than the predetermined time. The rapid rising of the pilot pressure in this manner has the meaning of switching the lock member to the release position in a state where the operation member is set in the activation position. Due to this, it is possible to accurately determine whether or not the operation member is set in the activation position when the lock member is switched to the release position. In addition, the erroneous operation monitoring section maintains the lock valve in the released state in a case where the pilot pressure is equal to or more than the predetermined pressure when the elapsed time is equal to or more than the predetermined time. The slow rising of the pilot pressure in this manner has the meaning of switching the lock member to the release position in a state where the operation member is not set in the activation position. Due to this, it is possible to accurately determine that the operation member is not set in the activation position when the lock member is switched to the release position.
In the work vehicle according to the second aspect of the present invention, it is possible to find and set the predetermined time using either experiments in advance or simulation.
In the work vehicle according to the third aspect of the present invention, it is possible to accurately determine whether or not the operation member is operated in the activation position when the lock member is switched to the release position.
In the work vehicle according to the fourth aspect of the present invention, it is possible to block the pilot pressure which is output through a plurality of fluid passages using one lock valve even in a case where the lock valve is connected to the plurality of pilot fluid passages in the pilot valve.
In the work vehicle according to the fifth aspect of the present invention, the lock valve is switched between the released state and the locked state according to activating of the lock member using the signal which is transmitted through the first signal line. It is possible for the controller to detect the lock member being positioned in either of the locked position or the release position using the signal which is transmitted through the second signal line. It is possible for the controller to detect the pilot pressure using the signal transmitted through the third signal line. It is possible for the controller to switch the lock valve to the locked state regardless of the activation of the lock member by sending a relay signal through the fourth signal line.
In the work vehicle according to the sixth aspect of the present invention, it is possible to more reliably suppress the unexpected activation of the hydraulic actuator when the lock member is switched to the release position.
In the work vehicle according to the seventh aspect of the present invention, it is possible to reliably suppress the unexpected activation of the hydraulic actuator.
In the work vehicle according to the eighth aspect of the present invention, it is possible for the operator to recognize erroneous operating of the operation member when the lock member is switched to the release position using notification from the notification section.
In the work vehicle according to the ninth aspect of the present invention, it is possible to more accurately determine whether or not the operation member is set in the activation position when the lock member is switched to the release position.
In the work vehicle according to the tenth aspect of the present invention, it is possible to perform the determination described above using the pilot pressure of any of the revolving motor, the hydraulic motor for movement, the boom cylinder, the arm cylinder, or the bucket cylinder.
In the control method of a work vehicle according to the eleventh aspect of the present invention, the lock valve is switched to the released state from the locked state when the lock member is switched to the release position from the locked position. However, the lock valve is switched to the locked state when the elapsed time is less than the predetermined time. The elapsed time being less than the predetermined time has the meaning of the pilot pressure rapidly rising since the lock member is switched to the released position. Due to this, it is possible to accurately determine whether or not the operation member is set in the activation position when the lock member is switched to the release position. In addition, the lock valve is maintained in the released state when the elapsed time is equal to or more than the predetermined time. The elapsed time being equal to or more than the predetermined time has the meaning of the pilot pressure slowly rising since the lock member is switched to the released position. Due to this, it is possible to accurately determine that the operation member is not set in the activation position when the lock member is switched to the release position.
In the control method of a work vehicle according to the twelfth aspect of the present invention, the lock valve is switched from the locked state to the released state when the lock member is switched from the locked position to the release position. However, the lock valve is switched to the locked state in a case where the pilot pressure rises to the predetermined pressure within the predetermined time after the lock member is switched from the locked position to the release position. That is, the lock valve is switched to the locked state in a case where the pilot pressure rapidly rises since the lock member is switched to the released position. Accordingly, it is possible to accurately determine whether or not the operation member is operated to be in the activation position when the lock member is switched to the release position.